H. Peter Anvin writes:> Richard Gooch wrote:> > > > Actually, there is some impedance matching. I've seen monitors with> > hi/lo impedance switches. And I've used 15 m long high-quality VGA> > cables. The result has been pretty good.> > > > The best I've seen is to use Sun D-sub coax or plain coax inputs on> the monitors that have them. Those are impedance matched and can be> extended without problem.

Sure, coax inputs are the best. But there are still problems. Evenexpensive coax has higher attenuation at higher frequencies, so thelonger the cable, the more fuzziness you get. Also, there aredifferential delay effects between the R, G and B components. Youdon't want the pixel components to arrive at different times. Sothere's a length limitation there as well.But even though coax is better, VGA isn't that bad. 15 m gets youquite a lot of terminals in a web kiosk (or undergrad computer lab).